Friction and screw press for the manufacture of ceramic articles



Dec. 26, 1967 u. WALCHHUTTER 3,359,608

FRICTION AND SCREW PRESS FOR THE MANUFACTURE OF CERAMIC ARTICLES FiledMarch 24, 1964 5 Sheets-Sheet 1 Dec. 26, 1967 u. WALCHHUTTER 3,359,608

FRICTION AND SCREW PRESS FOR THE MANUFACTURE OF CERAMIC ARTICLES 5Sheets-Sheet 2 Filed March 24, 1964 Dec. 26, 1967 u. WALCHHUTTER3,359,608

FRICTION AND SCREW PRESS FOR THE MANUFACTURE OF CERAMIC ARTICLES 5Sheets-Sheet :5

Filed March 24, 1964 flfllllm Dec. 26, 1967 u. WALCHHUTTER 3,359,608

FRICTION AND SCREW PRESS FOR THE MANUFACTURE OF CERAMIC ARTICLES FiledMarch 24, 1964 5 Sheets-Sheet 4 I Dec. 26, 1967 u. WALCHHUTTER 3,

FRICTION AND SCREW PRESS FOR THE MANUFACTURE OF CERAMIQARTICLES FiledMarch 24, 1964 5 Sheets-Sheet 5 United States Patent FRICTION AND SCREWPRESS FOR THE MANU- FACTURE OF CERAMIC ARTICLES Ulrico Walchhiitter, ViaAbamonti 2, Milan, Italy Filed Mar. 24, 1964, Ser. No. 354,223

Claims priority, application Italy, Mar. 27, 1963,

6,251/63, 6,252/63; Mar. 17, 1964, 5,961/64 13 Claims. (Cl. 25-45) Thisinvention relates to improvement in friction and screw presses for themanufacture of ceramic articles, as

tiles, mosaic tiles and the like ceramic products, said improvementsintended to increase the safety, and to avoid some drawbacks observed inexisting presses for this purpose.

A first object of this invention is to obtain a means to regulate andpreestablish one time for all the hoisting of the mobile traverse.

Another object of this invention is to obtain the elimination of the socalled pastille play between the mobile traverse and the screw end,which requires a supplementary stroke .of the screw, and consequently anincrease of the period of time for compressing of the ceramic material.

A further object of this invention is to maintain said mobile traverseindependent from the press screw at a position the traverse has reachedafter its first downwards compression stroke, while said screw isrecalled upwards in order to be newly thrown downwards for carrying outthe second and strong compressing stroke together with said mobiletraverse and their cooperating devices, in order to render the pressscrew lighter, by relieving it from the weight of the mobile traverseand its accessories, and from the work necessary to move thesecomponents, thus facilitating the screwing and unscrewing movements ofthe press screw.

Still another object of this invention is to eliminate the electromagnetfor controlling the disc for the up and down movement of the pressscrew, and to replace it by a hydraulic jack, thus simplifying all theequipment of the friction press for its automatic operation.

Still a further object of this invention is to control the movement ofthe mobile traverse of the press by means of hydraulic jacks.

An object of the invention is also to obtain the synchronization of themovements of the several components of the machine by means of a solehydraulic circuit and by using the combination through said hydrauliccircuit of the hydraulic devices respectively controlling the movementsof the mobile traverse, of the lower plungers of the molds, the moldmatrix and the rotating disc.

It is also an object of this invention to change the conditions andsteps of compression of the ceramic material within the molds in thesense to complete the usual pressing operations obtained by means of thepress screw by pre-compression steps which are obtained by exerting ontothe mobile traverse of the press a pro-compression throw, thisindependently from the press screw, and by maintaining a certainpressure on the material also in the period of time between the firstand the final compression steps, in order to eliminate the air enclosedwithin the mass of material in the molds, said air being the cause ofirregular, often unusable tiles and the like articles, particularly whenspecial ceramic material and the like are used for the manufacture ofsaid tiles.

A further object of this invention is to control the said pressurebetween the first and the second steps of compression in such a manneras to favor the elimination of the air in accordance with the kind andcomposition of the mass used for, this variation of pressure to becontrolled or reduced until a zero value, f.i. in the case of materialwherein the expelling of the air takes place spontaneously due to theswelling of the material which is due in turn to the pressure of the airwithin the mass of material to be compressed.

A further object of this invention is to provide for a lubricatingsystem so that the screw and cooperating devices may be forciblylubricated by making use of the movement of the press screw so that theoil is sucked from an oil container and pressed along the threadedportion of the screw, and exhausted back into the said container.

These and further objects and advantages of the invention will resultfrom the specification hereunder given of the same in an example ofembodiment also illustrated on the attached drawings, and of which:

FIGURE 1 is a front view, partially in section of a press according tothe invention;

FIGURE 2 shows the hydraulic circuit for controlling said press;

FIGURE 3 represents a view of the mobile traverse sustaining elements,according to a variant of the inventron;

FIGURE 4 shows the hydraulic circuit controlling the friction and screwpress of FIGURE 3; and

FIGURE 5 illustrates in a larger scale the lubricating system accordingto the invention.

Referring to FIGURE 1, a friction and screw press is composed as usualof a base plate 1, two uprights 2 and 3 projecting from the latter andsustaining at their upper ends a fixed traverse or press head 4 providedwith two arms turned upwards in order to support a continuously rotatingshaft 5 enabled to be alternately shifted in-axial direction, said shaftbearing two friction discs or wheels 6 and 7, the purpose of which is tofrictionally move with a left or right hand rotating movement a flywheel8 fixedly connected to the upper end of the press screw 9 which is moveddownwards and upwards within a threaded bushing located in the centerportion of the fixed upper press head 4, so that when one of saidfriction discs 6 or 7, frictionally engages the flywheel 8 the screw 9runs upwards and when the otherfriction disc 7 or 6 frictionally engagessaid flywheel 8 said screw 9 runs downwards in order to effect thecompression through the mobile traverse 11 and the respectiveaccessories of the mass within the mold or molds, thus converting thekinetic force of the flywheel into a compressing force onto the mobiletraverse.

Usually a cycle of compacting operations is composed of two successivecompression steps as follows:

A first light compression step in order to let the air. contained withinthe mass to be compressed, that is to say between the elements of saidmass to go out, and to distribute the latter conveniently within themold or molds, and

A second strong or more energetic compression step in order to impart tothe article under treatment the necessary compactness and mechanicalresistance so that the article may be used for the purpose for which itis manufactured.

The mobile traverse 11 is displaced along both press uprights 2 and 3and sustains the upper plungers 12 of the molds; this mobile traverse issupported in known similar presses directly at the lower screw end or bymeans of parallel situated rods in respect of the press screw, said rodsbeing attached to appropriate smaller horizontal controlling rods.

In the known presses, the mobile traverse 11 effects a first compressingstep, broadly similar to that of the screw, with the exception of a playleft between said mobile traverse and the lower end of the screw, saidplay being normally called pastille play (because it corresponds to thethickness of the article manufactured thereon), and which causes themobile traverse not to ascend again after the first compression step hastaken place, or, at most, to only go up again for a very small distance,but allowing the screw to run during the upwards stroke and thebeginning of the final compression step to move in upwards direction adistance equal to said pastille play, thus producing on said screw asupplementary load which corresponds to the weight of the mobiletraverse 11 plus the necessary force to move the latter.

The mold used, at least in the present embodiment of FIGURE 1, pertainsto the type molds in which the matrix 13 may be displaced downwards andsustained by means of at least two hydraulic jacks 14 and 15, by takingaccount that the plungers 12 have dimensions which are larger than thoseof the corresponding mold cavities.

In this mold type, the lowerplungers or bottom plates 16 are moved by ahydraulic device comprising two in series inserted hydraulic jacks 17and 18, as schematically shown in FIGURE 1.

According to this invention, the screw extends at its upper end througha cup-shaped member 19 fastened to the fixed traverse 4 and the upperpart of press screw is engaged by bearings 20 of appropriate makecarried by cap 19, while its lower part extends through a secondcup-shaped member 21, and is engaged by bearings 22 carried'by thesecond cap 21, whereby the screw is properly guided.

A bushing 23 is screwed on the caps 21, and is set once for all tomaintain its lower edge which serves as stopping member for the upwardmovement of the mobile traverse 11 at a selected elevation.

Still in accordance with this invention, the mobile traverse 11 is mademechanically independent from the press screw 9,'and is bilaterallysustained by hydraulic jacks 24 and'25, respectively.

Said hydraulic jacks have the task to recall saidmobile traverse 11upwards after each compression stroke, and to maintain it at its upperposition until the press screw 9 will move downwards and move saidmobile traverse in the same direction, by overcoming the fluid pressureas there will be explained further hereinafter) within the hydraulicjacks 24 and 25; the latter have also the purpose to stop the mobiletraverse at its lower position as the second compression step takesplace, this importing a raising and descending step of the screw.

Still in accordance with this invention, the control of the shaft 5,which bears the friction discs or wheels 6 and 7, driving the screwrotation flywheel 8 takes place bymeans of the hydraulic jack 27,through the transmission rod 26, and of its leverage, the purpose ofwhich being to replace the usual electromagnet used in combination withsaid rod 26, this with the view to simplify the electric or electronicequipment for the automatic operation of the press, whereby an advantageis obtained in the sense that all the protection and controlling devicesfor said electromagnet are rendered superfluous and consequentlyabolished.

Of course, in accordance with the purpose to avoid the aforesaidpastille play, all usual dead movements of the press and thecorresponding intervals of time, which are otherwise indispensabletherebetween, are wholly avoided. Furthermore, the existing possibilityto hoist the mobile traverse to a constant level permits to simplify thelocation of all cleaning devices for maintaining the mold or molds inperfect conditions of cleanliness, in particular in the case of theupper mold plungers or covering plates; f.i by using a rotatory brushfor such cleaning, it is possible to locate said brush at an exactelevation, thus avoiding all suspended or suspending flexible or elasticmeans, which were required in the past, and constituting a complicatedand costly equipment for the filling carriage of the press molds.

A set of levers forthe rod 26 is intended to act in combination with anarm 28, which is bent in such manner as to extend over the friction disc7 with the purpose to control the downwards stroke of the screw, thisserving to contact the flywheel 8 and following its movements through asmall roller 29, said arm being lifted together with the flywheel duringthe second upwards stroke of the latter in order to control the leveragewhich in turn controls the rod 26 in order to ensure the exactpositioning of the friction disc 7 with respect to the flywheel 8 inorder to brake and stop it at the required level. There is thus provideda safety member with the purpose to mechanically brake said flywheel atthe end of each one cycle of operations, and furthermore to control themeans for the automatic operation of the press.

FIGURE 2 shows the hydraulic equipment, with which the press of FIGURE 1is provided. The hydraulic equipment is constructed to ensure acooperation of all these hydraulic devices or hydraulic jacks which arenecessary to control the friction-screw press in accordance with thisinvention.

Said hydraulic equipment comprises a high pressure pumping set, composedof the pump 30 and the electric motor 31; said pumping set supplies thefluid under pressure to a conduit 32, cooperating with a hydrauliccompensator 33'. Conduit 32 is divided into a first conduit 33 to feedthe hydraulic jack 27 for controlling the two friction disc 6 and 7bearing shaft 5, said feeding taking place through an electromagneticvalve 34, which, when turned to one direction, allows the fluid underpressure to reach and invest the hydraulic jack 27, while, when turnedto the opposite direction, allows exhausting of the fluid therefrom.Downstream of the electromagnetic valve 34, still in said conduit 33 athrottle valve is inserted, which has a regulatable passage, and a checkvalve 36 in parallel to the throttle valve, the first one used tocontrol the inlet stream speed of the fluid under pressure into thecylinder of the hydraulic jack 27, and the second to permit a quickexhausing of the fluid.

The high pressure conduit 32 is further divided into a conduit 37 whichis in turn divided into two conduits, the one 37 being intercepted by anelectromagnetic valve 38, and the other 37" being intercepted by anelectromagnetic valve 39.

The electromagnetic valve 38 controls feeding of pressure fluid into thehydraulic jack 17 in order to control the lifting device of the lowermold plungers or covering plates, or the exhausting of said jack. Theelectromagnetic valve 39 permits feeding of pressure fluid into thehydraulic jack 18, and in turn its exhausting valve 39 permits at thesame time feeding of pressure fluid, through conduits 40, 41, 42 and 43,into hydraulic jack 24 or 25, the one or the other sustaining the mobiletraverse 11 of the press, and into hydraulic jack 14 or 15, the one orthe other sustaining the mold matrix. Conduit 40 is intercepted by anon-return valve 44 which impedes the return of the fluid under pressureto the conduit 37".

Conduit 41 is intercepted by an electromagnetic valve 45 serving tocontrol the opening and closing of a valve 46 used for establishing themaximum pressure checked in order to ensure the communication with theexhaust exclusively when said valve is put under a larger pressure thannecessary for operation of the press in question. The usual operationpressure of the press being about atm. (about 13,750 lbs. p.s.i.), saidvalve will be set for 600 atm. (about 82,500 lbs. p.s.i.).

Conduits 41 and 43 communicate with the high pressure conduit 32 througha conduit 47 which is intercepted by a non-return valve 48 permittingthe arrival of the high pressure fluid into the high pressure conduit 32without any possibility of return.

The above described arrangement will result that the upwards stroke ofthe lower plungers of the molds, under the intervening of the hydraulicjacks 17 and 18, of the matrix, under the intervening of the hydraulicjacks 14 and 18, and of the mobile traverse =11, under the interveningof the hydraulic jacks 24 and 25, can take place in the same time, sothat once the second step of the compacting of the ceramic mass has beencarried out,

and while the press screw begins its upwards stroke, all the lower moldplungers 16, the matrix and the mobile traverse 11 also are brought backto their upper position, so that the tiles are still subjected tocompression. Thus the matrix will stop as first, while the lowerplungers and the said mobile traverse, still continuing to press thetiles, will move further upwards at the same speed as the screw,contrasting the hydraulic jacks until the lower plungers will reach thesame level as the matrix during the extraction of the tiles from theirmold cavities, then stopping at this position reached. Finally, themobile traverse will continue along its upwards stroke to finally stopon abutting against the bushing 23.

The advantage of this form of extraction is that the tiles can notswell. Said extraction form has also the advantage that the tiles cannotspring outside the mold cavities onto the plungers at the instant oftheir extraction, especially because of their too quick displacement.Any deterioration of said tiles is therefore avoided.

From the equipment of FIGURE 2 it further results that once the hoistingof the mobile traverse has taken place, by feeding pressure fluid intothe hydraulic jacks 24 and 25, the closing of the electromagnetic valve45 stops the fluid stream contained therein, so that the mobile traverseis maintained at the upper position reached, without any possibility tolower spontaneously, should the screw 9 accidentally act onto the mobiletraverse. Checking of the security valve at the maximum pressureavailable remains intact, also when the flywheel, for being thrown inunforeseen manner, should shock with force the mobile traverse, whichmovement would provoke the exhausing of a small quantity of pressurefluid from the jacks, said small fluid quantity being but alwayssufficient to absorb the energy produced by this unforeseen movement ofthe screw.

Said suspension of the mobile traverse, besides giving a supplementarysecurity for the correct operation of the press, also provides for theprotection of the filling carriage of the press molds.

From the equipment of FIGURE 2 there is further to observe that, whenthe mobile traverse is displaced to its lower position, this beingprovoked by the throwing screw 9, and due to the opening of theelectromagnetic valve 45, and also when said mobile traverse will reston said matrix, lowering it, the pairs of hydraulic jacks 2425 and 14-15will be submitted to an increase of pressure so that the fluid containedtherein will surpass the maximum pressure checked by the security valveand will exhaust through the conduits 41 and 43, returning to thecontainer 33', by traversing the non-return valve 48 and the conduit 32,the non-return valve 49 impeding the return of the fluid to the pumpingset 30, 31. There is obtained the advantage to convert the kineticenergy of the flywheel 8 of the press to a compression force, saidconversion deriving from the braking moment of said flywheel at the timeof recording the first step of compression. The non-return valve 48,once the pistons of the jacks will have wholly entered their cylinders,impedes that the latter be newly submitted to pressure, so that both themobile traverse and the matrix will remain at the lower positionimmediately after the first step of compression, and furthermore for allthe time of duration of the operation of compression, that is to saytill the instant at which the electromagnetic valve 39 will control thefeeding of said jacks, as already exhibited hereinabove.

Referring now to FIGURE 3, the hydraulic jacks 24 and 25 are of thedouble action type. Their cylinders rest on brackets 24' and 25 fastenedto the press base plate, while their pistons are connected with themobile traverse through hinges 24" and 25".

Besides said jacks 24 and 25, two further hydraulic jacks 49 and 500fthe single action kindare fed in such a manner as to show the constanttendency to expand. The piston ends of jacks 49 and 50 are provided withregulatable members 51 and 52, the purpose of which 6 is to ensure theirexact positioning at the required level. The piston shaft ends 51 and 52are set at such a level as to ensure the cooperation with the mobiletraverse, or eventually with rigid connecting members of said mobiletraverse, as the latter is displaced from the position at which it isresting to that position wherein it contacts the molds to the positionwhich it assumes immediately after the complying of the first step ofcompression, the whole so that within the travel followed by the mobiletraverse the cited jacks 49 and 50 are put into the condition to exert athrow upwards against said mobile traverse.

As it will be seen in the following, the pressure of the fluid to feedthe jacks 49 and 50 may be checked once for all in the sense ofsubmitting the throw of said jacks exerted onto the mobile traverse 11exclusively during this travel. Generally said, the throw exerted by thehydraulic jacks 49 and 50 i smaller than that exerted downwards by thejacks 24, 25, so that as a general proceeding a downwards throw willtake place, the speed of which Will de pend mainly from the importanceof the contrasting throw exerted by the jacks 49 and 50. The inventioncomprises also the case wherein the pressure within the jacks 49 and 50will reach such a value that the upwards directed throw will be equal tothe whole effort produced by the throw of the jacks 24 and 25, as wellas deriving from the weight of the mobile traverse itself. v

The hydraulic controlling circuit of the press according to thisinvention is represented in FIGURE 4, wherein but a variant has beenintroduced to the arrangement of FIGURE 2.

As a matter of fact, in the examination of said FIGURE 4 in more detail,there is therein to observe that the feed-- ing set for the hydraulicjack 27, the purpose of which is to provide for the axial displacementof the two friction dlSCS supporting shaft 5, and the set composed ofmembers 30, 31 and 33' for the formation of the fluid pressure are notchanged at all.

The upper rooms of the jacks 24 and 25 are fed through a conduit 53; infree communication with the high pres-.

sure conduit 32, such that said rooms are submitted to fluid pressurewithout any interruption. The lower rooms of said jacks 24 and 25 arefed with high pressure fluid through the conduit 37, the electromagneticvalve 59 and the conduit 40, thus reaching a circuit composed of'twoparallel branches. The first one, 54, of these branches ensures a-directfeeding of the jacks as the electromagnetic valve 39 opens. The other ofsaid branches,-55, comprises the electro-magnetic valve 45 which, whenclosed, impedes the return of, pressure fluid to the conduit 40, while,when opened, it permits said return, comprising further the valve 46 setfor the maximum pressure of operationof the press, besides of a throttlevalve 56 to be checked at will, and connected in parallel with a furthervalve 57. The latter is controlled by mechanical means, more preciselyby means of a cam 58 provided on the mobile traverse 11 (FIGURE 3).Theposition of valve 57 is such that it is closed shortly before theupper plungers of the molds, 12, contact the matrix, thus forcing thefluid to exhaust through the throttle valve 56, so that the last portionof the downwards stroke is submitted to braking with the purpose toavoid a too hard engagement of the plungers with said matrix.

Both hydraulic jacks 14 and 15, which sustain the matrix, are fedthrough two hydraulic circuits, the first of which is formed by theelectromagnetic valve 39 and the conduit 40, further comprising athrottle valve 59, a nonreturn valve 60 and a cock 61. The second ofthese hydraulic circuits derives fromthe compression conduit 32 andcomprises a non-return valve 62 and a throttling plungers should loweronto the molds, the latter in turn lowering so as to cause theexhausting of a small quantity of fluid past valve 64 and cock 65 backto the conduit 32. In this manner, and also due to the fact that thematrix is constantly thrown back upwards, said matrix will constantlyrest against the upper plungers 12 also during the brief movements ofthe latter during the compression cycle, a separation taking place onlyat the end of this operating cycle, as the mobile traverse will havetaken again its upper position.

When cock 65 is closed, and cock 61 open, the feeding of the highpressure fluid into the hydraulic jacks 14 and 15 takes place from theconduit 40, past the throttle valve 59, non-return valve 60 and cock 61.When the matrix is forcefully moved downwardly by the mobile traverse,the high pressure fluid cannot return into the conduit 40 because of theblocking caused by the non-return valve 60, but may pass through thenon-return valves 64 and 62 in order to reach the conduit 32. Althoughthe communication with the valve 39 remains open, the hydraulic jacks 14and 15 do not receive any pressure fluid, because the valve 39due to thelowering of the mobile traverse 11- in the exhausting position, suchthat the matrix remains lowered and consequently doesnt follow themovements of the upper plungers, which thus are enabled to detach fromthem, also only for a short portion of the upwards stroke.

The hydraulic jacks 49 and 50 are fed from a hydraulic circuit derivedfrom the high pressure conduit 32. A cock 66, a safety valve 67 with anaccording gauge 68 for controlling the pressure value, and a pressureaccumulating device 69 are foreseen in connection with this feedingconduit.'The safety valve 67 is regul'atable, so that once it has beenset for a certain value there will be no possibility for the hydrauliccircuit to surpass the preestablished limit of the pressure. In such asituation, because of opening the cock 66, a pressure will beestablished in conduit 70 which will be equal to that which was set bymeans of the safety valve 67 and controlled by the gauge 68, after whichthe cock 66 will be closed again in order to provide in this way ablocked circuit in condition to feed a constant pressure to thehydraulic jacks 49 and 50. The variations of volume within the interiorof the jack rooms, and which will be due to the effort of the mobiletraverse during its'downwards stroke, will be compensated by thepressure accumulator 69.

A complete cycle of compression operations obtained by means of thehereabove mentioned equipment comprises the following steps:

(a) A filling step.During this step, valves 38 and 39 are open at thebeginning; their task is to maintain jacks 17 and 18 under pressure,such that the lower plungers of the molds are located at the level ofthe matrix. The lower rooms of jacks 24 and 25 are under pressure. Thereis thus obtained an upwards thrust against the lower faces of thepistons of said jacks, higher than that applied onto the upper faces ofsaid pistons, inasmuch as the areas of the upper faces are smaller dueto the presence of the piston shafts. The mobile traverse is thereforelifted to its upper position, at which it remains blocked following theintervening of the electromagnetic valve 45, the safety valve 46 and thenon-return member connected to the conduit 54.

Also the matrix is lifted, since the jacks 14 and 15 are under pressure,due to feeding of pressure fluid through the cock 65, and through thecock 61. The filling carriage, which is not represented for beinguniversally known, will now move forward, consequently discharging fromthe press the tiles manufactured in the preceding cycle of operations.At the same instant the electromag netic valve 38 is moved to itsexhaust position, such that jack 17 lowers, and the plungers are movedto the position of filling, thus permitting the filling operation bysaid carriage. The latter is then moved back and as soon as it isoutside the matrix zone, the valve 39 is moved to its exhaustingposition, thus causing the lowering of the hydraulic jack 18, and theplungers to rest onto the base plate of the press.

(b) A preliminary compression step.For this operation, valve 39 is inexhaust position, the electromagnetic valve 45 will open, so that thepressure fluid discharges from the lower rooms of the jacks 24 and 25thus traversing quickly the throttle member 56 and the correspondingvalve 57. Shortly before the plungers contact the matrix 13, member 58controls the valve 57 in order to have it in blocking position, so thatthe pressure fluid will be constrained to travel only through thethrottle member 56, thus considerably reducing the speed of the mobiletraverse to avoid a too rapid engagement of the plungers 12 with thematrix. Thus the mobile traverse may smoothly contact said matrix, whichis in turn also lowered, thus forcing some pressure fluid to dischargefrom the hydraulic jacks 14 and 15. Following the one or the other ofthe aforesaid cases of operation, the matrix can also be furthersubjected to a movement by means of the jacks 14 and 15, or be broughtto a stop, respectively. Whatever may be the instant conditions, themobile traverse will eflect the compression of the material in the moldby also exerting a force resulting from the action of the hydraulicjacks 24 and 25 plus its own weight against the counterforce provided bythe jacks 14 and 15.

(c) A first compression step.-For this operation, pressure fluid fedinto jack 27 causes axial displacement of shaft 5 of the two frictiondisc 6, 7 in order to start rotation of the flywheel 8, which in turncauses downward movement of the mobile traverse 11. The speed of thisdownward movement has to be regulated according to the kind andcomposition of the mass of ceramic material to be compressed, impartingto said flywheel a more or less forced braking action before any furthercompression occurs, by moving the jack 27 to its exhausting position.This step of compression causes the reduction of the thickness of themass within the press molds, such that both the mobile traverse 11 andthe upper mold plungers 12 move from the position of precompression to alower level. Immediately after the compression of the material, theflywheel 8 is inverted in its rotation, so as to be recalled upwards,thus drawing again in the same direction its screw 9. During itsdisplacement downwards the mobile traverse meets the shaft ends 51 and52 of the hydraulic jacks 49 and 50, which impart to the mobile traversean opposed throw. In order to regulate the compression force, it is alsonecessary to take in account the mechanical resistance possessed by theceramic mass to be compacted, and also that of the two jacks.

(d) An air exhausting step-As soon as the screw starts on its upwardsstroke, the mobile traverse of the press is still subjected to thedownward force imparted thereto by the jacks 24 and 25, on one side, andto the upward force imparted by the jacks 49 and 50, on the other side,so that the mass is maintained under a certain pressure in order toforce the air contained therein out from the molds. As already pointedout, the first step of compression of the material provokes a swellingof it, due to the air contained therein, and further also due to acertain factor of elasticity of the material itself.

In the case of particular material, from which the air cannot beliberated at the first step of compression it is necessary to leave themass for a sufficient period of time under compression to exhaust theair by passing the intervals existing between the particles of thematerial and the mold walls.

For these operations the jacks 14 and 15 are fed from the hydrauliccircuit which connects them to the condu t 32, such that the matrix ismaintained to rest with force against the upper plungers 12, while thecounterpressure produced by the jacks 49 and 50 will be maintainedsmaller than the total force exerted by the mobile traverse.

In case of masses of materials susceptible to be at once liberated ofthe air contained therein, that is to say already under the first stepof compression, the jacks 14 and 15 are fed with fluid under pressure bymeans of the electromagnetic valve 39; this fluid pressure provided tofeed the jacks 49 and 50 is checked in such a manner that the latterprovide a throw equal to the total effort produced by the mobiletraverse. In this case, the mass of material, besides of swelling duringthe first step of compression, also exerts a throw onto the plungers 12thus lifting the same for a very short stroke, suflicient to allow theair contained therein to exhaust. Due to the fact that the pressure ontothe mass of material remains unaltered during the whole interval betweenthe first and the second step of compression, there is the certaintythat all the air is exhausted from the molds of the press.

(e) A second compression step.In order to realize this second step ofcompression of the ceramic mass the flywheel 8 of the press is againrotated to move the mobile traverse 11 of the press with a larger forcedownwardly than for the first step of compression of the mass within thepress molds, to insure the final stamping of the ceramic articles to bemanufactured, at will. At the end of the compression the flywheeltravels immediately upwards, while the electromagnetic valves arecontrolled so that the lower plungers, the matrix and the mobiletraverse of the press will also return upwards, thus complying with allthe conditions already considered in referring to the FIGURES 1 and 2.Thus a successive cycle of operations may be repeated at will.

The aforesaid operations are based on the use of molds, the upperplungers are made in the form of covering plates, the sizes of which arelarger than those of the mold cavities, so that said covering plates arebrought in direct contact with the upper surface of the respective moldor molds, thus requiring a matrix of the kind as already consideredhereabove.

The use of larger plungers or covering plates is preferred because theproducts obtained from them are of a better appearance.

This appearance can be still further improved by the combination of themold with the improved press according to this invention, since the airis exhausted through the intervals of the lower plungers and the wallsof the matrix, while the pressure exerted by the plungers onto saidmatrix permits to conderably reduce the formation of burrs along theborders of the tiles or like articles. Any burrs which may be formed areof such a thinness, that they can be eliminated Without leaving anytrace, with the greatest simplicity and quickness.

The improved press according to this invention is also usable with moldshaving upper plungers entering the mold cavities. Of course, in thiscase, the matrix will be fixed in a stable position, and the hydraulicjacks 14 and 15 together with their corresponding equipment and circuitsfor feeding them with pressure fluid are eliminated. The remainingelements and devices are unchanged, and so is also the operation.

A further advantage which can be realized with the press of thisinvention is represented by the factas already stated hereabove-that thedischarge of the air from the mass in the mold takes place slower,laterally of the upper plungers of the mold, so that the latter will notbe soiled with residues transported by the air on exhausting, also incase the molds have to be heated, as it was necessary to do till now.

This advantage appears to be ascribed to the fact that during the firststep of compression, and due to the adiathermic compression, the airwhich is eventually heated, has all the time necessary to cool incontacting the mass of material to be compressed, such that its slowexhausting will notprovoke any condensation of steam onto the faces ofthe plungers. Of course the means which serve to realize a step ofprecompression and a step of final compression of the mass, after thepreliminary com pression, are usable also in the hydraulic presses whichhave to do with the same drawbacks as those mentioned in theintroduction to this specification of the invention.

Referring now to the FIGURE 5 of the drawings, 4 is the fixed uppertraverse of the press, said traverse having at its center portion athreaded bushing 10 for causing the up and down movement of the screw 9of the press.

The roller bearing 20 engages a cylindrical sleeve 71 fixed to an upperportion of. the screw spindle 9 and the outer surface of the sleeve '71is engaged by a packing 72 held by an appropriate ring 73 supported by abushing 74 which is screwed around the rim 75 of the cupshaped member19. In this manner the upper end of the threaded portion 76 of the screw9 of the press is sealed and the cup-shaped member 19 provides a strongprotecting means against any transversal movements and for the improvedguiding of said screw 9.

Thus there is formed between member 19 and the screw 9 of the press anannular space 77, which is fluid tightly sealed. This sealed spaceserves to prevent any leakage of lubricating oil, and it will alsoprevent introduction of dust and other impurities into said space andbetween bushing and screw.

As represented by FIGURE 5, when the screw 9 is fully lifted, lower end78 of its threaded portion is above the lower end of the threadedbushing 10, so that a cylindrical part 79 at the lower end of spindle 9forms together :with the internally threaded bushing 10 a second lowerspace 80. The cylindrical part 79 projects into the internal surface 81of another cupshaped member 21, which is fastened to the traverse 4 bymeans of bolts 82. The length of the threaded portion of the spindle 9is about the same as that of the threaded bushing, the thread beingcalled to work only at the instant of the effective compression, inother words as the mechanical load is at its maximum. The space ishermetically closed by means of a packing 33 held by a ring 84 set atthe end of the member 21, said packing in turn embracing the cylindricalportion 79 of the screw 9. Said member 21 also bears a bearing of lining85 in order to engage the screw at its main lower portion, and toprotect it against cross loads, further pro viding a convenient guidingmeans in the vertical direction.

The space 80 can communicate through the intervals consented by ablocking ring 86 within the member 21 and the lining 85, with a conduit88. Space 77 communicates with an oil container 89 through a conduit 90,which is conveniently connected to the wall of the member 19.

Said last mentioned conduit enters the interior of said container89above the liquid level therein. Said room is in communication through aconduit 88 with another conduit 91 entering said container 89, and theend of which is submerged into the liquid, further bearing an oilfiltering member 92 in order to filter the lubrieating oil. Two one wayvalves 93 and 94 opening in opposite directions are provided in conduit91.

Valve 93 allows the passage of the oil from the container 89 to thespace 80 also when the sucking factor is a minimum, this being due tothe fact that this valve is deprived of any acting spring thereon.

Valve 94 allows the passage of the oil for lubricating only from thespace 80 to the oil container 89. This valve is held in place by aspring 95 so that the oil, which is directed to the oil container canreach the latter only when the oil pressure will reach such a value asto be enabled to open valve 32.

When the press screw 9 is put into rotation from its upper position, asshown in the FIGURE 5, thus effecting its downward stroke, the thread 76provokes a reduction of volume within the space 80. The oil isconsequently compressed and sent all along said thread of the screw 9and the bushing 10 till it reaches the space 77. If the pressure of theoil surpasses the pre-established maximum value of pressure, valve 94opens so that a part of the lubricating oil at least will return to theoil container 89.

When the screw returns to its upper position, this movement will causean increase of the volume within the room 80, there will be causetherein a partial vacuum, by means of which lubricating oil will besucked from the oil container through conduit 91, valve 93 and conduit88. In the same time, and following the return upwards of the screw, thevolume of room 77 decreases, so that the oil therein enclosed is sentback to conduit 90 in order to be discharged into the oil container 89.

It appears from the above that the invention provides a system for theforced lubrication of suflicient simplicity and immediate function,because of the valve 94, and without provoking any brakage upon saidscrew 9.

From the space 77 air will be sucked from the container and for thisreason the latter is provided with an air filter 34 in order to impedethe entering of impurities into the lubricating system.

Of course, the invention may be realized in other forms also of a largedilterent mode, without giving out of the boundaries of the same, asthose skilled in the art will well understand.

What I claim is:

1. A tile press comprising, in combination, a base having an uppersurface; a fixed traverse; support means sup porting said fixed traversein fixed position upwardly spaced from said upper surface of said base;a movable traverse located in the space between-said upper surface andsaid fixed traverse and being guided on said support means for movementtoward and away from said upper surface; a threaded bushing carried bysaid fixed traverse and having an axis substantially normal to saidupper surface; a screw spindle extending through said bushingthreadingly engaged therewith and having a lower end abutting againstsaid movable traverse; friction drive means cooperating with said screwspindle to turn the latter in one and in the opposite direction aboutits axis to thereby move said spindle in axial direction so that saidlower end of said spindle will exert during downward movement thereof adownward pressure on said movable traverse; hydraulic jack means carriedby said base and cooperating with said movable traverse; means forcontrolling flow of pressure fluid into and out from said hydraulic jackmeans so .as to impart an upward pressure smaller than the downwardpressure produced by said spindle; upper mold means carried by saidmovable traverse; and lower mold means carried by said base.

2. A tile press as defined in claim 1, wherein said friction drive meanscomprise a shaft turnably carried by said fixed traverse above thelatter substantially normal to the axis of said spindle and movable indirection of its own axis, a pair of friction discs carried spaced fromeach other by said shaft for rotation therewith, a flywheel locatedbetween said friction discs and fixed to the upper end of said spindle,hydraulic means for shifting the shaft in axial direction to alternatelybring said friction discs in contact with said flywheel, and controlmeans controlling said hydraulic means in dependence on the position ofsaid flywheel.

3. A tile press as defined in claim 1, wherein said means forcontrolling flow of pressure fluid into and out from said hydraulic jackmeans include a hydraulic pressure accumulator so connected to saidhydraulic jack means that the fluid pressure increase created thereinduring downward pressure of said screw spindle on said movable traverseis stored in said hydraulic pressure accumulator.

4. A tile press as defined in claim 3, and including safety valve meansin circuit with said hydraulic jack means and said hydraulic pressureaccumulator.

5. A tile press as defined in claim 1, and including upper and lowerguide means on said fixed traverse for guiding said screw spindle insaid axial direction, said lower guide means including stop meanscooperating with said movable traverse for stopping upward movement ofthe latter under the influence of said hydraulic jack means.

6. A tile press as defined in claim 1, wherein said lower mold meansinclude a matrix and plate means movable relative to said matrix betweena lower filling position and an upper ejecting position, and includingfurther hydraulic jack means mounted on said base and yieldablysupporting said matrix above said upper surface of said base, additionalhydraulic jack means connected to and cooperating with said plate meansfor moving the latter between said positions thereof, and means forcontrolling flow of pressure fluid into and out from said further andadditional hydraulic jack means.

7. A tile press as defined in claim 1, wherein said hydraulic jack meanscomprise a pair of single acting hydraulic jacks engaging said movabletraverse at laterally spaced portions thereof for imparting to thelatter only an upwardly directed force.

8. A tile press as defined in claim 1, wherein said hydraulic jack meanscomprise a pair of double acting hydraulic jacks each having a pistonconnected to said movable traverse respectively at laterally spacedportions of the latter, and wherein said means for controlling flow offluid into and out of said hydraulic jack means are arranged to.alternatingly fee-d pressure fluid to one side of each piston anddischarge pressure fluid from the other side thereof and vice versa sothat said double acting hydraulic jacks may also be used for imparting adownward pressure to said movable traverse independent from said spindleto thus impart a precompression onto mate-rial in said mold means.

9. A tile press as defined in claim 8, and including single actinghydraulic jack means mounted on said base upwardly projecting therefrom,said single acting hydraulic jack means having upper acting endsengaging said movable traverse when the latter is pressed downwardly.

10. A tile press as defined in claim 1, and including means forming apair of sealed annular lubricating spaces at opposite ends of said screwbushing about said screw spindle, and means on said screw spindle forrespectively increasing and decreasing the volume of at least one ofsaid lubricating spaces during axial movement of said spindle so as toforce lubricating oil in said spaces in axial direction along saidspindle.

11. A tile press as defined in claim 10, wherein said means forming saidlubricating spaces comprise a pair of cup-shaped members fixed to andrespectively projecting upwardly and downwardly from said fixed traversecoaxial with said screw spindle, and sealing means on said cup-shapedmembers and engaging said spindle.

12. A tile press as defined in claim 11, and including an oil reservoir,a pair of conduit-s connecting said oil reservoir with said lubricatingspaces, respectively, one of said pair of conduits connecting said onelubricating space with said oil reservoir having an end in said oilreservoir below the level of lubricating oil therein, and the otherconduit having an end in said oil reservoir above said level, and a pairof oppositely directed oneway valves connected in parallel to said oneconduit.

13. A tile press as defined in claim 11, and including guide meanscarried by said cup-shaped members and engaging said spindle for guidingthe same in axial direction.

References Cited UNITED STATES PATENTS 1,503,619 8/1924 Zeh 25-551,790,041 1/1931 Crossley 25-45 2,770,862 11/1956 Miller 2584 X3,036,355 5/1962 Mays et al. 2545 3,044,138 7/1962 Lesnett et al. 2584 X3,097,411 7/1963 Gerster et a1 25-45 FOREIGN PATENTS 597,050 8/ 1959Italy.

I. SPENCER OVERHOLSER, Primary Examiner.

R. S. ANNEAR, Assistant Examiner.

1. A TILE PRESS COMPRISING, IN COMBINATION, A BASE HAVING AN UPPERSURFACE; A FIXED TRAVERSE; SUPPORT MEANS SUPPORTING SAID FIXED TRAVERSEIN FIXED POSITION UPWARDLY SPACED FROM SAID UPPER SURFACE OF SAID BASE;A MOVABLE TRAVERSE LOCATED IN THE SPACE BETWEEN SAID UPPER SURFACE ANDSAID FIXED TRAVERSE AND BEING GUIDED ON SAID SUPPORT MEAND FOR MOVEMENTTOWARD AND AWAY FROM SAID UPPER SURFACE; A THREADED BUSHING CARRIED BYSAID FIXED TRAVERSE AND HAVING AN AXIS SUBSTANTIALLY NORMAL TO SAIDUPPER SURFACE; A SCREW SPINDLE EXTENDING THROUGH SAID BUSHINGTHREADINGLY ENGAGED THEREWITH AND HAVING A LOWER END ABUTTING AGAINSTSAID MOVABLE TRAVERSE; FRICTION DRIVE MEANS COOPERTING WITH SAID SCREWSPINDLE TO TURN THE LATTER IN ONE AND IN THE OPPOSITE DIRECTION ABOUTITS AXIS TO THEREBY MOVE SAID SPINDLE IN AXIAL DIRECTION SO THAT SAIDLOWER END OF SAID SPINDLE WILL EXERT DURING DOWNWARD MOVEMENT THEREOF ADOWNWARD PRESSURE ON SAID MOVABLE TRAVERSE; HYDRAULIC JACK MEANS CARRIEDBY SAID BASE AND COOPERATING WITH SAID MOVABLE TRAVERSE; MEANS FORCONTROLLING FLOW OF PRESSURE FLUID INTO AND OUT FROM SAID HYDRAULIC JACKMEANS SO AS TO IMPART AN UPWARD PRESSURE SMALLER THAN THE DOWNWARDPRESSURE PRODUCED BY SAID SPINDLE; UPPER MOLD MEANS CARRIED BY SAIDMOVABLE TRAVERSE; AND LOWER MOLD MEANS CARRIED BY SAID BASE.